Wideband biconical antenna with helix feed for an above-mounted antenna

Abstract

A wideband biconical antenna arrangement is disclosed having a feed arrangement that services a second antenna positioned above the biconical antenna. The feed for the second antenna is configured as a helix that spirals around an outer periphery of the upper and lower cones of the biconical antenna along the biconical antenna's cylindrical radiating aperture. In one embodiment, the feed is a coaxial cable disposed within a hollow metal tube. This helix feed does not substantially degrade the performance of the wideband biconical antenna. The wideband biconical antenna has its feed disposed within a central conduit of the biconical antenna. The biconical antenna has at least one octave of bandwidth, and in one embodiment the second antenna also has at least one octave of bandwidth.

1. An antenna arrangement, comprising:
 a wideband biconical antenna including first and second three-dimensional cones; 
 a second antenna mounted above said wideband biconical antenna; 
 wherein the second antenna has a feed configured in a helical shape such that the second antenna feed is substantially within a generally cylindrical volume defined by the outer diameters of a base of each of the first and second three-dimensional cones of said wideband biconical antenna and such that the second antenna feed does not substantially degrade the performance of the wideband biconical antenna. 
 
     
     
       2. The antenna arrangement of  claim 1 , wherein the second antenna feed does not substantially degrade the biconical antenna's input impedance or gain radiation patterns. 
     
     
       3. The antenna arrangement of  claim 1 , wherein the second antenna feed is asymmetrical in azimuth and does not substantially degrade gain variation of the second antenna. 
     
     
       4. The antenna arrangement of  claim 1 , wherein a feed for the wideband biconical antenna is disposed within a central shaft of the wideband biconical antenna. 
     
     
       5. The antenna arrangement of  claim 1 , wherein the second antenna feed comprises a coaxial cable disposed within a hollow tube. 
     
     
       6. The antenna arrangement of  claim 1 , wherein the biconical antenna has at least one octave of bandwidth. 
     
     
       7. The antenna arrangement of  claim 1 , wherein the second antenna has at least one of a frequency band, a radiation pattern, and a broadband characteristic that is different from that of the biconical antenna. 
     
     
       8. The antenna arrangement of  claim 7 , wherein the second antenna has at least one octave of bandwidth. 
     
     
       9. A multi-antenna arrangement, comprising:
 a wideband biconical antenna including first and second three-dimensional cones; 
 a second antenna mounted above said wideband biconical antenna, the second antenna having a feed mounted within a tube formed into a helix shape such that it spirals substantially within a generally cylindrical volume defined by an outer edge of a base of each of the first and second three-dimensional cones of the wideband biconical antenna along the wideband biconical antenna's cylindrical radiating aperture; 
 wherein the second antenna feed does not substantially degrade the performance of the wideband biconical antenna. 
 
     
     
       10. The antenna arrangement of  claim 9 , wherein the second antenna feed does not substantially degrade the biconical antenna's input impedance or gain radiation patterns. 
     
     
       11. The antenna arrangement of  claim 9 , wherein the second antenna feed is asymmetrical in azimuth and does not substantially degrade gain variation of the second antenna. 
     
     
       12. The antenna arrangement of  claim 9 , wherein a feed for the wideband biconical antenna is disposed within a central shaft of the wideband biconical antenna. 
     
     
       13. The antenna arrangement of  claim 9 , wherein the second antenna feed comprises a coaxial cable disposed within a hollow tube. 
     
     
       14. The antenna arrangement of  claim 9 , wherein the biconical antenna has at least one octave of bandwidth. 
     
     
       15. The antenna arrangement of  claim 9 , wherein the second antenna has at least one of a frequency band, a radiation pattern, and a broadband characteristic that is different from that of the biconical antenna. 
     
     
       16. The antenna arrangement of  claim 15 , wherein the second antenna has at least one octave of bandwidth. 
     
     
       17. A vertically mounted antenna arrangement, comprising:
 a wideband biconical antenna including upper and lower three dimensional cones, said wideband biconical antenna having a feed disposed within a central conduit of the antenna; and 
 a second antenna mounted above said upper cone, the second antenna having a coaxial feed disposed within a tube; 
 wherein the tube is formed in a helix shape that spirals substantially within a generally cylindrical volume defined by an outer periphery of the upper and lower cones along the wideband biconical antenna's cylindrical radiating aperture; and 
 wherein the second antenna feed does not substantially degrade the performance of the wideband biconical antenna. 
 
     
     
       18. The antenna arrangement of  claim 17 , wherein the second antenna feed tube helix is asymmetrical in azimuth and does not substantially degrade the wideband biconical antenna's input impedance or gain radiation patterns. 
     
     
       19. The antenna arrangement of  claim 18 , wherein the wideband biconical antenna has at least one octave of bandwidth. 
     
     
       20. The antenna arrangement of  claim 19 , wherein the second antenna has at least one octave of bandwidth.